Conventionally, there is known a door stopper for locking a door in an open state. A door stopper is generally constituted by a hook member arranged on the door, and a protruding part that is arranged to be protruding from the floor surface or the wall surface and that can lock the hook.
The hook member is usually provided at a position at the bottom part of the door near the floor. Therefore, in order to use the door stopper to lock the door in an open state, the operator makes a low posture (bends lower) after opening the door, and engages the hook member provided on the door with the protruding part.
However, this operation is troublesome. Therefore, there is proposed a door stopper having a configuration in which the door is locked along with the motion of opening the door, and the lock is released by operating the door again (Patent Document 1). The door stopper disclosed in Patent document 1 has a configuration provided with a stopper movable body that can oscillate in the vertical and horizontal directions with respect to the floor surface, and includes a stopper fixed body that is arranged on the floor and that locks the door by engaging with the stopper movable body along with the movement of the door.